/*
 * Copyright 2013 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.buffer;


import io.netty.util.internal.PlatformDependent;

import java.nio.ByteBuffer;


/**
 * Read-only ByteBuf which wraps a read-only direct ByteBuffer and use unsafe for best performance.
 */
final class ReadOnlyUnsafeDirectByteBuf extends ReadOnlyByteBufferBuf {

  private final long memoryAddress;

  ReadOnlyUnsafeDirectByteBuf(ByteBufAllocator allocator, ByteBuffer byteBuffer) {
    super(allocator, byteBuffer);
    // Use buffer as the super class will slice the passed in ByteBuffer which means the memoryAddress
    // may be different if the position != 0.
    memoryAddress = PlatformDependent.directBufferAddress(buffer);
  }

  @Override
  protected byte _getByte(int index) {
    return UnsafeByteBufUtil.getByte(addr(index));
  }

  @Override
  protected short _getShort(int index) {
    return UnsafeByteBufUtil.getShort(addr(index));
  }

  @Override
  protected int _getUnsignedMedium(int index) {
    return UnsafeByteBufUtil.getUnsignedMedium(addr(index));
  }

  @Override
  protected int _getInt(int index) {
    return UnsafeByteBufUtil.getInt(addr(index));
  }

  @Override
  protected long _getLong(int index) {
    return UnsafeByteBufUtil.getLong(addr(index));
  }

  @Override
  public ByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
    checkIndex(index, length);
    if (dst == null) {
      throw new NullPointerException("dst");
    }
    if (dstIndex < 0 || dstIndex > dst.capacity() - length) {
      throw new IndexOutOfBoundsException("dstIndex: " + dstIndex);
    }

    if (dst.hasMemoryAddress()) {
      PlatformDependent.copyMemory(addr(index), dst.memoryAddress() + dstIndex, length);
    } else if (dst.hasArray()) {
      PlatformDependent.copyMemory(addr(index), dst.array(), dst.arrayOffset() + dstIndex, length);
    } else {
      dst.setBytes(dstIndex, this, index, length);
    }
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
    checkIndex(index, length);
    if (dst == null) {
      throw new NullPointerException("dst");
    }
    if (dstIndex < 0 || dstIndex > dst.length - length) {
      throw new IndexOutOfBoundsException(String.format(
          "dstIndex: %d, length: %d (expected: range(0, %d))", dstIndex, length, dst.length));
    }

    if (length != 0) {
      PlatformDependent.copyMemory(addr(index), dst, dstIndex, length);
    }
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, ByteBuffer dst) {
    checkIndex(index);
    if (dst == null) {
      throw new NullPointerException("dst");
    }

    int bytesToCopy = Math.min(capacity() - index, dst.remaining());
    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + bytesToCopy);
    dst.put(tmpBuf);
    return this;
  }

  @Override
  public ByteBuf copy(int index, int length) {
    checkIndex(index, length);
    ByteBuf copy = alloc().directBuffer(length, maxCapacity());
    if (length != 0) {
      if (copy.hasMemoryAddress()) {
        PlatformDependent.copyMemory(addr(index), copy.memoryAddress(), length);
        copy.setIndex(0, length);
      } else {
        copy.writeBytes(this, index, length);
      }
    }
    return copy;
  }

  @Override
  public boolean hasMemoryAddress() {
    return true;
  }

  @Override
  public long memoryAddress() {
    return memoryAddress;
  }

  private long addr(int index) {
    return memoryAddress + index;
  }
}
